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Water may still flow on the surface of Mars today

At least some water likely still flows on the surface of Mars, a new study suggests.

New data from NASA's Mars Reconnaissance Orbiter lends more evidence to the theory that extremely salty brines flow on Mars seasonally, likely creating those dark streaks on Martian slopes that the spacecraft has observed. This new finding could also have some broad implications for extinct and perhaps current life on Mars.

This discovery may solve a long-running mystery about the creation of the dark, thin streaks (called recurring slope lineae) that appear during warmer Martian months and fade during cool seasons. Basically, the new data lends more credence to the long-running hypothesis that, at least sometimes, a small amount of water flows down slopes on Mars.

"Under certain circumstances liquid water might be found on Mars," NASA's division of planetary science director Jim Green said during a press conference about the findings Monday.

The Martian water is likely too salty to support life as we currently understand it, according to the new study published Monday in the journal Nature Geoscience. But the authors stress that "the detection described here warrants further astrobiological characterization and exploration of these unique regions on Mars."

"Experience in the driest places on Earth tells us that life is very creative at taking advantage of very small amounts of water to survive and even thrive," Alfonso Davila, a SETI researcher unaffiliated with the new study, told Mashable via email.

"Therefore this study adds to a growing body of evidence that the Martian habitability window might have closed not billions of years ago with the disappearance of lakes, as is commonly assumed, but much more recently."

The surface temperatures in locations where the recurring slope lineae are active do point to salty liquid water flowing on the slopes, but it's not a sure thing.

Recurring slope lineae on Mars flowing downhill.

Image: NASA/JPL/University of Arizona

The Mars Reconnaissance Orbiter didn't find any direct evidence of water or salt in the collected data, according to the study, though the craft did find evidence for hydrated salts at the areas, which is the best-ever direct evidence of flowing water on the planet.

Also, scientists still aren't sure where the water flows actually come from.

Researchers have hypothesized that the water could be from the melting of ice at or just below the planet's surface, "but the presence of near-surface ice at equatorial latitudes is highly unlikely," according to the study.

The recurring slope lineae might also develop as a result of a process known as deliquescence — a chemical process by which a material absorbs atmospheric moisture until it dissolves into a solution.

Recurring slope lineae.

The most wide-reaching implications for the recurring slope lineae finding might actually be limited to Mars' past.

"If the data indeed point to liquid water being responsible for the formation of RSL [recurring slope lineae], we are still talking about meager amounts of liquid water that might form locally during certain seasons," Davila said.

"But this still is a very significant finding because if tiny amounts of liquid water can occur on Mars today, then liquid water activity could have been more prevalent in the not-so-distant past."

It's possible that NASA's Curiosity rover might actually be able to shed some light on this liquid water mystery at some point on its journey up Mount Sharp, NASA said. The mountain actually could play host to recurring slope lineae, but more research is needed before that's known for sure.

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